High-entropy alloys (HEAs) have been reported to have better properties than conventional materials; however, they are more expensive due to the high cost of their main components. Therefore, research is needed to reduce manufacturing costs. In this study, CoCrFeMnNi HEAs were prepared using metal injection molding (MIM), which is a powder metallurgy process that involves less material waste than machining process. Although the MIM-processed samples were in the face-centered cubic (FCC) phase, porosity remained after sintering at 1200°C, 1250°C, and 1275°C. In this study, the hot isostatic pressing (HIP) process, which considers both temperature (1150°C) and pressure (150 MPa), was adopted to improve the quality of the MIM samples. Although the hardness of the HIP-treated samples decreased slightly and the Mn composition was significantly reduced, the process effectively eliminated many pores that remained after the 1275°C MIM process. The HIP process can improve the quality of the alloy.

Heavy water primary system decontamination technology is essential to reduce worker exposure and improve safety during maintenance and decommissioning of nuclear facilities. Advanced decontamination technology development aims to secure controlled decontamination technologies that can reduce the cost of radiation exposure and dramatically reduce the amount of secondary waste generated when decontaminating large equipment and large-area facilities. We conducted a study to identify candidate corrosion inhibitors through the literature and analyze the degree of corrosion of carbon steel samples. Countries with advanced nuclear technology have developed chemical decontamination technology for the entire nuclear power generation system and applied it to the dismantling and maintenance of nuclear power plants. In the decontamination process, the corrosion oxide film must be removed. If the base metal is corroded by the decontaminant in this process, additional secondary waste is generated and treatment costs increase. Therefore, it is necessary to develop a corrosion inhibitor that inhibits the corrosion of the carbon steel base metal in the decontamination process to generate a secondary waste liquid that is favorable for waste reduction and treatment. In this presentation, a study was conducted to analyze the extent of corrosion on a carbon steel base material and identify candidate materials for corrosion inhibition testing. Samples were analyzed using optical microscopy and EPMA analysis to determine the thickness of the corroded oxide film. EPMA analysis also allowed us to map the elemental distribution of the carbon steel corrosion layer, which we plan to quantify in the future. The candidate materials for organic-based corrosion inhibitor were also selected based on their inhibition mechanism; having high electronegative elements for coordinate covalent bonding at metal surface and hydrophobic nonpolar group for preventing access of corrosive substances.The selection of candidate materials for corrosion inhibition testing was based on the mechanism of the corrosion inhibitor. Organic-based corrosion inhibitors are adsorbed by donor-acceptor interactions between metal surfaces and highly electronegative elements. Corrosion can also be inhibited by arranging hydrophobic nonpolar groups on metal surfaces in the solution direction to prevent access of corrosive substances.

Natural uranium-contaminated soil in Korea Atomic Energy Research Institute (KAERI) was generated by decommissioning of the natural uranium conversion facility in 2010. Some of the contaminated soil was expected to be clearance level, however the disposal cost burden is increasing because it is not classified in advance. In this study, pre-classification method is presented according to the ratio of naturally occurring radioactive material (NORM) and contaminated uranium in the soil. To verify the validity of the method, the verification of the uranium radioactivity concentration estimation method through γ-ray analysis results corrected by self-absorption using MCNP6.2, and the validity of the pre-classification method according to the net peak area ratio were evaluated. Estimating concentration for 238U and 235U with γ-ray analysis using HPGe (GC3018) and MCNP6.2 was verified by 􀟙-spectrometry. The analysis results of different methods were within the deviation range. Clearance screening factors (CSFs) were derived through MCNP6.2, and net peak area ratio were calculated at 295.21 keV, 351.92 keV(214Pb), 609.31 keV, 1120.28 keV, 1764.49 keV(214Bi) of to the 92.59 keV. CSFs for contaminated soil and natural soil were compared with U/Pb ratio. CSFs and radioactivity concentrations were measured, and the deviation from the 60 minute measurement results was compared in natural soil. Pre-classification is possible using by CSFs measured for more than 5 minutes to the average concentration of 214Pb or 214Bi in contaminated soil. In this study, the pre-classification method of clearance determination in contaminated soil was evaluated, and it was relatively accurate in a shorter measurement time than the method using the concentrations. This method is expected to be used as a simple pre-classification method through additional research.

In general, after the decommissioning of nuclear facilities, buildings on the site can be demolished or reused. The NSSC (Nuclear Safety and Security Commission) Notice No. 2021-11 suggests that when reusing the building on the decommissioning site, a safety assessment should be performed to confirm the effect of residual radioactivity. However, in Korea, there are currently no decommissioning experiences of nuclear power plants, and the experiences of building reuse safety assessment are also insufficient. Therefore, in this study, we analyzed the foreign cases of building reuse safety assessment after decommissioning of nuclear facilities. In this study, we investigated the Yankee Rowe nuclear power plant, Rancho Seco nuclear power plant, and Hematite fuel cycle facility. For each case, the source term, exposure scenario, exposure pathway, input parameter, and building DCGLs were analyzed. In the case of source term, each facility selected 9~26 radionuclides according to the characteristics of facilities. In the case of exposure scenario, building occupancy scenario which individuals occupy in reusing buildings was selected for all cases. Additionally, Rancho Seco also selected building renovation scenario for maintenance of building. All facilities selected 5 exposure pathways, 1) external exposure directly from a source, 2) external exposure by air submersion, 3) external exposure by deposited on the floor and wall, 4) internal exposure by inhalation, and 5) internal exposure by inadvertent ingestion. For the assessment, we used RESRAD-BUILD code for deriving building DCGLs. Input parameters are classified into building parameter, receptor parameter, and source parameter. Building parameter includes compartment height and area, receptor parameter includes indoor occupancy fraction, ingestion rate, and inhalation rate, and source parameter includes source thickness and density. The input parameters were differently selected according to the characteristics of each nuclear facility. Finally, they derived building DCGLs based on the selected source term, exposure scenario, exposure pathway, and input parameters. As a result, it was found that the maximum DCGL was 1.40×108 dpm/100 cm2, 1.30×107 dpm/100 cm2, and 1.41×109 dpm/100 cm2 for Yankee Rowe nuclear power plant, Rancho Seco nuclear power plant, and Hematite fuel cycle facility, respectively. In this study, we investigated the case of building reuse safety assessment after decommissioning of the Yankee Rowe nuclear power Plant, Rancho Seco nuclear power plant, and Hematite fuel cycle facility. Source terms, exposure scenarios, exposure pathways, input parameters, and building DCGLs were analyzed, and they were found to be different depending on the characteristics of the building. This study is expected to be used in the future building reuse safety assessment after decommissioning of domestic nuclear power plants. This work was

The aim of this study was to investigate the effect of isolated lactic acid bacteria (LAB) on the quality of high moisture rye silage. Rye forage (Secale cereale L.) was harvested at the heading stage (27.3% of dry matter (DM)) and cut into approximately 3-5 cm lengths. Then, the forage divided into 4 treatments with different inoculants: 1) No additives (CON); 2) Lactobacillus brevis strain 100D8 at a 1.2 x 105 colony-forming unit (cfu)/g of fresh forage (LBR); 3) Leuconostoc holzapfelii strain 5H4 at a 1.0 x 105 cfu/g of fresh forage (LHO); and 4) Mixture of LBR and LHO (1:1 ratio) applied at a 1.0 x 105 cfu/g of fresh forage (MIX). About 3 kg of forage from each treatment was ensiled into a 20 L mini-bucket silo in quadruplicate for 100 days. After silo opening, silage was collected for analyses of chemical compositions, in vitro nutrient digestibilities, fermentation characteristics, and microbial enumerations. The CON silage had the highest concentrations of neutral detergent fiber and acid detergent fiber (p = 0.006; p = 0.008) and a lowest in vitro DM digestibility (p < 0.001). The pH was highest in CON silage, while lowest in LBR and MIX silages (p < 0.001). The concentrations of ammonia-N, lactate, and acetate were highest in LBR silage (p = 0.008; p < 0.001; p < 0.001). Propionate and butyrate concentrations were highest in CON silage (p = 0.004; p < 0.001). The LAB and yeast counts were higher in CON and LHO silages compare to LBR and MIX silages (p < 0.001). However, the mold did not detect in all treatments. Therefore, this study could conclude that L. brevis 100D8 and Leu. holzapfelii strain 5H4 can improve the digestibility and anti-fungal activity of high moisture rye silage.

A laser scabbling experiment was performed using a high-power fiber laser to investigate the removal rate of the concrete block and the scabbled depth. Concrete specimens with a 28-day compressive strength of 30 MPa were used in this study. Initially, we conducted the scabbling experiment under a stationary laser beam condition to determine the optimum scan speed. The laser interaction time with the concrete surface varied between 3 s and 40 s. The degree of spalling and vitrification on the surface was primarily dependent on the laser interaction time and beam power. Furthermore, thermal images were captured to investigate the spatial and temporal distribution of temperature during the scabbling process. Based on the experimental results, the scan speed at which the optical head moved over the concrete was set to be 300 mm∙min−1 or 600 mm∙min−1 for the 4.8-kW or 6.8-kW laser beam, respectively. The spalling rates and average depth on the concrete blocks were measured to be 87 cm3∙min−1 or 227 cm3∙min−1 and 6.9 mm or 9.8 mm with the 4.8-kW or 6.8-kW laser beams, respectively.

스탠다드국화 신품종을 육성하기 위하여 충남농업기술원 화훼연구소에서 2009년에 황색의 모본 ‘Summer Yellow’와 부본 ‘ST07-09-02’계통을 인공 교배하였다. 2010년에 종자를 파종하였고, 이중 내병성이 강하고 기호성이 우수한 개체를 선발하여 ‘ST10-047-01’로 계통명을 부여하였다. 2011년부터 2013년까지 주년 생산성을 위해 촉성 및 자연, 억제재배 특성을 각각 검정하였으며, 2013년 ‘Geumhwa’로 명명하고 품종등록 출원하였다. ‘Geumhwa’의 생육 및 개화특성은 국내에서 많이 재배되고 있는 황색 스탠다드국화인 ‘Summer Yellow’를 대조 품종으로 하여 조사하였다. ‘Geumhwa’ 품종은 자연개화기가 10월 6일로 ‘Summer Yellow’의 10월 25일에 비해 빨랐다. ‘Geumhwa’는 초장이 86.3cm로 ‘Summer Yellow’의 93.8cm보다 작았고, 곁가지 제거수는 8.1개로 ‘Summer Yellow’의 16.6개보다 적었다. ‘Geumhwa’의 꽃직경은 13.6cm로 ‘Summer Yellow’의 13.5cm와 비슷하였으며, 꽃잎수는 ‘Geumhwa’가 263.6개로 ‘Summer Yellow’의 295.3개보다 적었다. 재배상 유의사항은 ‘Geumhwa’는 중간종이므로 초기생육이 왕성하도록 비배 관리를 하고 생육기간 중 지베렐린 1,000mg･L-1를 2회 처리하여 신장력을 높이도록 한다. 또한 설상화수가 적은 편이므로 재전조를 실시하여 설상화수를 늘린다면 황색의 연중 조기개화가 가능한 고품질 신품종 스탠다드 절화국화로써 소비자 기호 충족 및 농가소득 창출에 기여할 수 있을 것으로 기대된다.

동남아시아에 발생하던 등검은말벌은 최근 국내 뿐만 아니라 프랑스와 일본, 유럽 전역으로 확산되어 전 세계 양봉 산업에 극심한 피해를 주고 있다. 등검은말벌을 방제하기 위해 다양한 방제 방법들이 연구되고 있으며, 그 중 말벌 유인제에 대해 국제적으로 많은 연구가 진행되어 왔으나 이 역시 지속적인 개발이 필요한 실정이다. 따라서 본 연구에서는 시판 유인제와 최근 (주)다목에코텍에서 새롭게 개발한 신규 개발 유인제에 대한 효능 검정을 수행하였 고 양봉장에 출현하는 국내 발생 말벌속의 발생양상을 조사하였다. 담양 1개소와 곡성 2개소에 기존 유인제과 신규 유인제를 장착한 포획기를 각 3쌍씩 설치하여 2016년 9월부터 11월말까지 주 1~2회 관찰하였다. 그 결과 국내 발생 말벌속 중 등검은말벌(7,787 개체)이 가장 많이 포획되었고, 다음으로 장수말벌, 말벌, 좀말벌, 꼬마장수말벌, 털보말벌 순으로 포획되었다. 두 유인제의 포획력 검정 결과, 신규 개발 유인제가 통계적으로 유의하게(P < 0.01) 등검은말벌 포획력이 높음을 보였다.

The effects of cold storage temperature and exposure duration on immature stages of spotted-wing drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) on ‘Campbell Early’ grapes were examined to establish a phytosanitary control method. The immature stages (eggs, larvae and pupae) of SWD were all dead after a 6-day cold treatment at 1°C and 8-day cold treatment at 1.5 and 2°C. Small-scale tests using pupae, which were the most-cold tolerant stage, confirmed the validity of the selected temperature and exposure durations. Conversely, the 8- and 10-day at 1°C treatments showed 100% mortality, suggesting that these treatments can guarantee quarantine security against infestations of SWD on exported ‘Campbell Early’ grapes.

Porcine spermatogonial stem cells (SSCs) prefer three-dimensional (3D) culture systems to 2D ones for the maintenance of self-renewal. Of the many 3D culture systems, agar-based hydrogels are candidates for supporting porcine SSC self-renewal, and there are various types of agar powder that can be used. In this study, we sought to identify an agar-based 3D hydrogel system that exhibited strong efficacy in the maintenance of porcine SSC self-renewal. First, 3D hydrogels with different mechanics were prepared with various concentrations of Bacto agar, lysogeny broth (LB) agar, and agarose powder, and the 3D hydrogel with the strongest alkaline phosphatase (AP) activity and greatest increase in colony size was identified for the different types of agar powder. Second, among the porcine SSCs cultured in the different 3D hydrogels, we analyzed the colony formation, morphology, and size; AP activity; and transcription and translation of porcine SSC-related genes, and these were compared to determine the optimal 3D hydrogel system for the maintenance of porcine SSC self-renewal. We found that 0.6% (w/v) Bacto agar-, 1% (w/v) LB agar-, and 0.2% (w/v) agarose-based 3D hydrogels showed the strongest maintenance of AP activity and the most pronounced increase in colony size in the culture of porcine SSCs. Moreover, among these hydrogels, the strongest transcription and translation of porcine SSC-related genes and largest colony size were detected in porcine SSCs cultured in the 0.2% (w/v) agarose-based 3D hydrogel, whereas there were no significant differences in colony formation and morphology. These results demonstrate that the 0.2% (w/v) agarose-based 3D hydrogel can be effectively used for the maintenance of porcine SSC self-renewal.

We study the angular correlation function of bright (Ks ≤ 19.5) Extremely Red Objects (EROs) selected in the Subaru GTO 2 deg2 field. By applying the color selection criteria of R − Ks > 5.0, 5.5, and 6.0, we identify 9055, 4270, and 1777 EROs, respectively. The number density is consistent with similar studies on the optical − NIR color selected red galaxies. The angular correlation functions are derived for EROs with different limiting magnitude and different R −Ks color cut. When we assume that the angular correlation function w() follows a form of a power-law (i.e., w() = A−), the value of the amplitude A was larger for brighter EROs compared to the fainter EROs. The result suggests that the brighter, thus more massive high-redshift galaxies, are clustered more strongly compared to the less massive galaxies. Assuming that EROs have redshift distribution centered at hzi ∼ 1.1 with z = 0.15, the spatial correlation length r0 of the EROs estimated from the observed angular correlation function ranges ∼ 6-10 h−1Mpc. A comparison with the clustering of dark matter halos in numerical simulation suggests that the EROs are located in most massive dark matter halos and could be progenitors of L∗ elliptical galaxies.

방사성폐기물 발생기관의 가용데이터를 기반으로 산출된 핵종재고량을 적용하여 예비안전성평가를 수행한 결과 처분안전성과 운영측면에서 많은 어려움이 예상됨을 확인하였다. 본 논문에서는 전체처분시설 예비안전성평가를 수행하였으며, 평가결과 성능목표치 초과핵종에 대해 방사능량이 큰 비중을 차지하는 단위포장물을 선별하고, 높은 표면선량률의 포장물을 처분대상에서 제외하는 방식으로 처분시설의 처분방사능량제한을 도입하였다. 처분방사능량제한은 안전기준 만족을 위한 처분시설별 인수기준과 처분기준 설정에 기초자료로 활용할 것이며, 경주 처분시설의 안전한 종합개발계획수립 및 처분시 설의 안전성 최적화를 위한 Safety Case 구축에 기여할 것으로 판단된다.

Alzheimer’s disease (AD), a progressive neurodegenerative disorder that deprives the patient of memory, is associated mainly with extracellular senile plaque induced by the accumulation of amyloid β protein (Aβ). Silybum marianum (Asteraceae; SM) is a medicinal plant that has long been used in traditional medicine as a hepatoprotective remedy owing to its antioxidant and anti-inflammatory activities. The present study examined the methanol extract of the aerial parts of SM for neuroprotection against Aβ (25-35)-induced neuronal death in cultured rat cortical neurons to investigate a possible therapeutic role of SM in AD. The primary cortical neuron cultures were prepared using embryonic day 15 to 16 SD rat fetuses. Cultured cortical neurons exposed to 10 μM Aβ (25-35) for 36 h underwent neuronal cell death. At 10 and 50 μg/mL, SM prevented Aβ (25-35)-induced neuronal cell death and apoptosis in cultured cortical neurons. Furthermore, SM inhibited the Aβ (25-35)-induced decrease in anti-apoptotic protein, Bcl-2, and the increase in the proapoptotic proteins, Bax and active caspase-3. Cultured cortical neurons exposed to 1 mM N-methyl-D-aspartate (NMDA) for 14 h induced neuronal cell death. SM (10 and 50 μg/mL) prevented NMDA-induced neuronal cell death. These results suggest that SM inhibited Aβ (25-35)-induced neuronal apoptotic death via inhibition of NMDA receptor activation and that SM has a possible therapeutic role in preventing the progression of neurodegeneration in AD.